This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Coxsackieviruses are members of the picornavirus family that rely on an interaction with an IgG-like receptor that binds into a depression in the virus surface called the canyon. This interaction causes a conformational change that destabilizes the virus and leads to uncoating. However, some strains of coxsackievirus B group have adapted also to use decay accelerating factor, DAF, as an additional receptor that binds outside of the canyon. These DAF binding variants have altered pathogenicity and preliminary studies show that binding of DAF has become necessary for infection. Preliminary structural studies suggest that when DAF binds CVB3 variants, the virus and the receptor both may undergo conformational changes. We have co-crystallized the virus interacting with the DAF receptor to investigate these changes.